Apparatus for the manipulation of plastic bags following a bag-making machine can comprise an input conveyor for receiving bag elements, a delivery unit with outer turnstiles spaced from one another according to the width of the bag elements, and a stacking unit.
The turnstiles can have a plurality of radially disposed suction arms to firmly grasp the bag elements received from the input conveyor and place the bag elements on the intermittently operated bag-stacking unit.
The stacking unit can have an endlessly running stacking conveyor belt with stacking pegs provided which are arranged in accordance with the stack spacing.
In a prior-art apparatus, for example that of German Pat. No. DE-OS 31 38 221, the stacking-apparatus conveyor has a single centrally running conveyor chain with two rows of pegs spaced side-by-side thereon. The transport apparatus has only the outer turnstiles which are spaced from one another.
The lack of a middle turnstile in the delivery apparatus is a disadvantage and apparently such construction was due to the fear of possible collision of a middle turnstile with the conveyor chain.
This previously described structure also limits the versatility of the known apparatus.
Further, the prior-art apparatus can only work with bag elements that are incompletely finished bags. It acts on almost flattened plastic foil strips which have edge welds running perpendicular to one another and are separated each from the other. Since, from these bag elements, two distinct bags are to be constructed, the stacking apparatus must be equipped with additional implements.
It is totally impossible to manufacture sine-shaped bags (i.e. bags with sinusoidal contours) of this invention using the prior-art apparatus. Sine-shaped bags are distinguished from previously known bags by having a more or less sine shape at the opening and at the hand grips. The prior-art bag-manipulating apparatus cannot work behind a bag-making machine which is equipped to produce this kind of sine-shaped bag (for comparison, see German Pat. Nos. DE-OS 30 04 220 and DE-OS 30 04 244).